The present disclosure relates generally to the field of weather display systems. More particularly, the present disclosure relates to a weather display system and method configured to provide latency compensation for data linked weather data.
Aircraft weather radar systems are often used to alert operators of vehicles, such as aircraft pilots, of weather hazards that may affect the aircraft. Such weather radar systems typically include an antenna, a receiver transmitter, a processor, and a display. The system transmits radar pulses or beams and receives radar return signals indicative of weather conditions. Conventional weather radar systems, such as the WXR 2100 MULTISCAN radar system manufactured by Rockwell Collins, Inc., have Doppler capabilities and can measure or detect parameters such as weather range, weather reflectivity, weather velocity, and weather spectral width or velocity variation. Weather radar systems may also detect outside air temperature, winds at altitude, INS G loads (in-situ turbulence), barometric pressure, humidity, etc.
Weather radar signals are processed to provide graphical images to a radar display. The radar display is typically a color display providing graphical images in color to represent the severity of the weather. Some aircraft systems also include other hazard warning systems such as a turbulence detection system. The turbulence detection system can provide indications of the presence of turbulence or other hazards. Conventional weather display systems are configured to display weather data in two dimensions and often operate according to ARINC 453 and 708 standards. A horizontal plan view provides an overview of weather patterns that may affect an aircraft mapped onto a horizontal plane. Generally the horizontal plan view provides images of weather conditions in the vicinity of the aircraft, such as indications of precipitation rates. Red, yellow, and green colors are typically used to symbolize areas of respective precipitation rates, and black color symbolizes areas of very little or no precipitation. Each color is associated with radar reflectivity range which corresponds to a respective precipitation rate range. Red indicates the highest rates of precipitation while green represents the lowest (non-zero) rates of precipitation. Certain displays may also utilize a magenta color to indicate regions of turbulence.
While aircraft-based weather radar systems may typically provide the most timely and directly relevant weather information to the aircraft crew based on scan time of a few seconds, the performance of aircraft-based weather radar systems may be limited in several ways. First, typical radar beam widths of aircraft-based weather radar systems are 3 to 10 degrees. Additionally, the range of aircraft-based weather radar systems is typically limited to about 300 nautical miles, and typically most effective within about 80-100 nautical miles. Further, aircraft-based weather radar systems may be subject to ground clutter when the radar beam intersects with terrain, or to path attenuation due to intense precipitation or rainfall.
Information provided by aircraft weather radar systems may be used in conjunction with weather information from other aircraft or ground-based systems to, for example, improve range and accuracy and to reduce gaps in radar coverage. For example, the National Weather Service WSR-88D Next Generation Radar (NEXRAD) weather radar system is conventionally used for detection and warning of severe weather conditions in the United States. NEXRAD data is typically more complete than data from aircraft-based weather radar systems due to its use of volume scans of up to 14 different elevation angles with a one degree beam width. Similarly, the National Lightning Detection Network (NLDN) may typically be a reliable source of information for weather conditions exhibiting intense convection. Weather satellite systems, such as the Geostationary Operational Environmental Satellite system (GOES) and Polar Operational Environmental Satellite system (POES) are other sources of data used for weather analyses and forecasts.
While NEXRAD has provided significant advancements in the detection and forecasting of weather, NEXRAD data may have gaps where no data is collected (e.g., due to cone of silence and umbrella of silence regions, insufficient update rates, geographic limitations, or terrain obstructions). Similarly, weather observations and ground infrastructure are conventionally limited over oceans and less-developed land regions. Providing weather radar information from aircraft systems to other aircraft systems and/or ground-based operations may provide significant improvement to weather observations and forecasts by filling such gaps in radar coverage. Similarly, providing weather radar information from ground-based systems to aircraft-based systems may increase the range and accuracy of aircraft-based systems in certain conditions.
One issue with sharing weather data among aircraft-based and ground-based weather radar systems is the discrepancy in apparent location of weather conditions due to the time delay associated with transmitting and displaying shared weather data. For example, depending on circumstances, latencies associated with transmission and delivery of uplinked weather radar data from a ground-based system to an aircraft-based system are commonly on the order of 5-10 minutes, and in some cases may be as long as 20 minutes. Ground-based weather radar systems may also have a lower update rate. Such latency issues have conventionally limited the use of uplinked weather radar data to longer range applications rather than shorter range tactical decisions.
Such latency issues are further compounded when multiple weather radar data sources are combined. Current systems typically provide individual displays for each data source, and often with display limitations that require the aircraft crew to form a mental image of an integrated display rather than actually viewing an integrated display. Furthermore, misalignments due to latency issues may result in increasing the size of threat regions such that longer diversions are required for an aircraft to avoid such enlarged threat regions. In addition, the various sensors used by each of the multiple weather data sources may provide dissimilar measurements for a weather condition, creating uncertainty in how to weight the data provided from each source. There is an ongoing need for improved weather radar systems and methods that provide a comprehensive integrated display of weather conditions using multiple weather radar data sources. There is yet further need for improved weather radar systems and methods that compensate for latency issues associated with sharing and fusing weather radar data among aircraft-based and ground-based systems to more accurately portray the threat posed by a weather condition. There is further need for improved weather radar systems and methods that provide a confidence factor reflecting the degree to which various input sources agree in their characterization of the severity of the threat posed by a weather condition.